Osteoporosis Flashcards
What is Parathyroid hormone (PTH)?
Polypeptide hormone produced by parathyroid glands
When is PTH released?
Released in response to decrease in free [Ca2+] plasma - Picked up by calcium-sensing receptors (CaSR) located on parathyroid (chief) cells.
What are the actions of PTH?
Acts to increase [Ca2+] by:
- Stimulating osteoclasts - 12-24hr effect
- Inhibit osteoblasts
- Decrease Ca2+ excretion at the kidneys
- Increasing renal excretion of phosphate
- Stimulates calcitriol synthesis - kidneys from vitamin D3
What is Calcitriol?
A steroid hormone produced by the kidneys and liver which complements the activity of PTH
How is Calcitriol synthesised?
What are the actions of Calcitriol?
Binds nuclear receptors in target tissue (intestine, bone, kidney):
- Increases absorption of Ca2+ from the gut
- Facilitates renal reabsorption of Ca2+
- Mobilises calcium stores in bone by stimulating osteoclast activity
What are the dietary sources of Vitamin D3?
- Fatty fish - mackerel and tuna
- Fish liver oils
- Egg yolks
What is the definition of Osteoporosis?
“Normal bone, not enough of it”
- A condition of skeletal fragility characterized by reduced bone mass and microarchitectural deterioration
- A result on DXA bone scanning <2.5 SDs below the young adult mean
How does Osteoporosis occur? (i.e. what is the pathogenesis?)
Bone mass decreases with age, but will depend on
- Peak bone mass - attained in adult life
- Rate of loss - in later life.
Mechanisms involved include:
- Failure to achieve adequate peak bone mass
- Increase in bone resorption
- Reduction in bone formation.
What are the causes of osteoporosis?
SHATTERED Family
- Steroid use
- Hyperthyroidism; hyperparathyroidism, hypercalciuria
- Alcohol and tobacco use
- Thin (BMI <22) - Anorexia nervosa
- Testosterone low (e.g. anti androgen in cancer of prostate)
- Early/post-menopause
- Renal or liver failure
- Erosive/inflammatory bone disease - RA, multiple myeloma, osteogenesis imperfecta
- Dietary Ca low/malabsorption or Diabetes mellitus type 1
- Family history
What are the Risk Factors of Osteoporosis which you would want to ask someone about?
- Smoking
- Alcohol
- Menopausal status
- Immobility/exercise
- Diseases which influence bone turnover - thyrotoxicosis, malabsorption, inflammatory arthritis
- Medications - steroid use
How does someone with osteoporosis present?
- MAINLY ASYMPTOMATIC - picked up incidentally or ini context of fragility fracture
- Fragility fractures
- Pain - from mechanical derangement
- Thoracic Kyphosis
- Height loss
- Features of underlying cause - e.g. signs of endocrine disorder such as cushings syndrome
What are the different types of fragility fractures seen in Osteoporosis?
THESE ARE RED FLAG FRACTURES FOR OSTEOPOROSIS
- Vertebral crush fractures
- Colle’s Fracture
- Fractures of proximal femur (#NOF)
- Shoulder Fracture
- Pubic Ramus Fracture
What is the differential diagnosis for fragility fractures?
- Osteoporosis
- Osteomalacia
- Paget’s disease
- Tumour - primary or metastatic
- Osteogeneis Imperfecta
What are vertebral crush fractures?
“Dowagers hump”
These are the most common fractures in osteoporosis - Wedge fracture of spinal vertebrae, which lead to kyphotic deformity
Fractures are mostly thoracic, can be lumbar, and are rarely cervical
Outcomes of the fracture include chronic pain (nerve entrapment), reduced QOL, decreased mobility and reduced chest compliance (FVC decreases 9% per vertebrae fractured).
What is a Colle’s Fracture?
Colles fractures are very common extra-articular fractures of the distal radius that occur as the result of a fall onto an outstretched hand (FOOSH)
What are the complications of a Colle’s Fracture?
Occurs in 20% of patients
- Malunion - dorsal angulation, radial deviation & shortening
- Stiffness - many #’s are intra-articular
- Median nerve entrapment - Carpal Tunnel Syndrome
- CRPS type 1
- Rupture of tendon of EPL - late complication due to impaired blood supply
What are the different types of hip fracture?
Can be NOF or proximal femoral fracture
Types include
- Intracapsular (50%)
- Displaced
- Undisplaced
- Extracapsular (50%)
- Basal cervical
- Subtrochanteric
- Intertrochanteric - 2 part comminuted
What are some of the complications of an Osteoporotic shoulder fracture?
- Axillary nerve palsy
- Malunion
- Stiffness
What clinical picture would indicate a possible Pubic ramus fracture?
- HISTORY OF A FALL
- Elderly (very)
- Female patient
- Unable to walk
- Pain & tenderness in groin and on leg movement
How would you treat a Pubic Ramus Fracture?
- Short period of bed rest (48h), then mobilise (with physiotherapy)
How would you determine who should be treated?
Can you name the classic deformity of a Colle’s Fracture, and the 5 components of this deformity?
Classic Deformity - DINNER FORK DEFORMITY
- Dorsal Angulation + Displacement
- Radial Shortening + Deviation
- Supination
What can be seen on this X-ray of the wrist of a 65 year old women after a fall onto an oustretched hand?
Colle’s Fracture
What is an intracapsular hip fracture?
Fracture of neck of femur inside the hip capsule
What is an extracapsular hip fracture?
Between insertion of hip joint capsule and 5cm below lesser trochanter
What are the different types of intracapsular hip fractures?
- Basal cervical
- Transcervical
- Subcapital
What are the different types of extracapsular hip fractures?
- Intertrochanteric
- Reverse oblique
- Subtrochanteric
What is the following type of fracture?
Intracapsular fracture
What is the classificaiton system used for intracapsular hip fractures?
Garden classification
What is shenton’s line?
Shenton line is an imaginary curved line drawn along the inferior border of the superior pubic ramus (superior border of the obturator foramen) and along the inferomedial border of the neck of femur.
